Display device

ABSTRACT

According to one embodiment, a display device includes a first substrate including an insulating substrate with a through hole, a first pad electrode disposed above the insulating substrate, and a signal line electrically connected to the first pad electrode, a second substrate disposed to be opposed to the first substrate, a first layer disposed between the first pad electrode and the second substrate, a wiring substrate including a connection line and disposed below the insulating substrate, and a conductive material disposed within the through hole to electrically connect the first pad electrode and the connection line, wherein the through hole is formed in a position overlapping the first layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2015-245375, filed Dec. 16, 2015, theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a display device.

BACKGROUND

In recent years, display devices with a greater display area on thesurface are highly anticipated because of higher performance andadvanced design in the technical field of mobile data communicationdevices such as mobile phone and personal digital assistant (PDA). Forexample, display devices including a thinner bezel structure areproposed.

Conventionally, there is a well-known structure in which a driver ismounted in the periphery of the display area on the substrate includingelectrodes. In display devices using such a structure of the driver,input signals and voltages are supplied to the driver through a wiringsubstrate such as a flexible printed circuit (FPC). However, inconsideration of greater production and thinner bezel structure, therehas been a study to omit such a flexible printed circuit but to achievean electrical connection between lines formed on the lower surface sideof an array substrate and the driver formed on the upper surface side ofthe array substrate through a contact hole passing through the arraysubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of the structure of a displaydevice of an embodiment.

FIG. 2 is a schematic plan view of the first substrate of the displaydevice of FIG. 1.

FIG. 3 is a cross-sectional view of a display area of the display deviceof FIG. 1.

FIG. 4A is a cross-sectional view of the display device of FIG. 1including a non-display area.

FIG. 4B is another cross-sectional view of the display device of FIG. 1including a non-display area.

FIG. 5 is a cross-sectional view of a variation of the display device ofthe embodiment.

FIG. 6 is a plan view of the first substrate of the embodiment, showinga pad electrode, contact hole, second spacer, and sealant.

FIG. 7 is a plan view of a variation of the first substrate SUB1 of theembodiment, showing a variation of the pad electrode PD, contact holeCHa, and second spacer SP2.

FIG. 8 is a cross-sectional view showing a first process in which thefirst substrate and the second substrate of the above embodiment areadhered together.

FIG. 9 is a cross-sectional view showing a second process in which thesupport substrate is partly peeled off from the first insulatingsubstrate and the contact hole is formed in the first substrate afterthe first process of FIG. 8.

FIG. 10 is a cross-sectional view showing a third process in which thewiring substrate is pressed to the liquid crystal display panel afterthe second process of FIG. 9.

FIG. 11 is a cross-sectional view of another variation of the displaydevice of the embodiment.

DETAILED DESCRIPTION

In general, according to one embodiment, a display device includes: afirst substrate including an insulating substrate with a through hole, afirst pad electrode disposed above the insulating substrate, and asignal line electrically connected to the first pad electrode; a secondsubstrate disposed to be opposed to the first substrate; a first layerdisposed between the first pad electrode and the second substrate; awiring substrate including a connection line and disposed below theinsulating substrate; and a conductive material disposed within thethrough hole to electrically connect the first pad electrode and theconnection line, wherein the through hole is formed in a positionoverlapping the first layer.

Embodiments will be described hereinafter with reference to theaccompanying drawings. Incidentally, the disclosure is merely anexample, and proper changes within the spirit of the invention, whichare easily conceivable by a skilled person, are included in the scope ofthe invention as a matter of course. In addition, in some cases, inorder to make the description clearer, the widths, thicknesses, shapes,etc. of the respective parts are schematically illustrated in thedrawings, compared to the actual modes. However, the schematicillustration is merely an example, and adds no restrictions to theinterpretation of the invention. Besides, in the specification anddrawings, the structural elements having functions, which are identicalor similar to the functions of the structural elements described inconnection with preceding drawings, are denoted by like referencenumerals, and an overlapping detailed description is omitted unlessnecessary.

Firstly, a display device of a present embodiment will be explained.FIG. 1 is a schematic perspective view showing the structure of adisplay device DSP of the present embodiment. FIG. 1 shows athree-dimensional space which is defined by a first direction X, seconddirection Y which is orthogonal to the first direction X, and thirddirection Z which is orthogonal to the first direction X and the seconddirection Y. Note that, in this example, the first direction X and thesecond direction Y are orthogonal to each other; however, they may crossat an angle other than 90°. Furthermore, in the present embodiment, thedisplay device is a liquid crystal display device.

As shown in FIG. 1, the display device DSP includes a liquid crystaldisplay panel PNL of active matrix type and a wiring substrate 1. Theliquid crystal display panel PNL includes a plate-like first substrateSUB1, plate-like second substrate SUB2 opposed to the first substrateSUB1, and liquid crystal layer (liquid crystal layer LQ which will bedescribed later) interposed between the first substrate SUB1 and thesecond substrate SUB2. Note that the liquid crystal display panel PNL ofthe present embodiment is a reflective-type liquid crystal displaypanel.

In the present embodiment, the positive direction of the third directionZ, that is, a direction from the first substrate SUB1 toward the secondsubstrate SUB2 is defined as up or above, and the negative direction ofthe third direction Z, that is, a direction from the second substrateSUB2 toward the first direction SUB1 is defined as down or below.

The liquid crystal display panel PNL includes a display area DA in whichan image is displayed and a non-display area NDA which surrounds thedisplay area DA. The liquid crystal display panel PNL includes aplurality of pixels PX within the display area DA. The pixels PX arearranged in a matrix in the first direction X and the second directionY.

In the example depicted, a side edge of the first substrate SUB1 whichis parallel to the first direction X and a side edge of the secondsubstrate SUB2 which is parallel to the first direction X have asubstantially same length. Furthermore, a side edge of the firstsubstrate SUB1 which is parallel to the second direction Y and a sideedge of the second substrate SUB2 which is parallel to the seconddirection Y have a substantially same length. That is, an area of thefirst substrate SUB1 which is parallel to the X-Y plane is substantiallythe same as an area of the second substrate SUB2 in the X-Y plane. Inthe present embodiment, each side edge of the first substrate SUB1matches each corresponding edge of the second substrate SUB2 in thethird direction Z.

The wiring substrate 1 is disposed below the liquid crystal displaypanel PNL. In this example, a side edge of the wiring substrate 1 whichis parallel to the first direction X has a length shorter than or equalto the side edges of the first substrate SUB1 and the second substrateSUB2 which are parallel to the first direction X. Furthermore, a sideedge of the wiring substrate 1 which is parallel to the second directionY has a length shorter than or equal to the side edges the firstsubstrate SUB1 and the second substrate SUB2 which are parallel to thesecond direction Y. The wiring substrate 1 is disposed in both thenon-display area NDA and the display area DA. In the present embodiment,a side edge of the wiring substrate 1 which is parallel to the firstdirection X matches an end of the liquid crystal display panel PNL inthe third direction Z. Note that the wiring substrate 1 does not gooutside the area opposed to the liquid crystal display panel PNL. Theliquid crystal display panel PNL and the wiring substrate 1 areelectrically connected to each other.

FIG. 2 is a schematic plan view of the first substrate SUB1 of thedisplay device DSP of FIG. 1. As shown in FIG. 2, the first substrateSUB1 includes, in the display area DA, a plurality of gate lines Gextending in the first direction X and arranged in the second directionY, a plurality of source lines S extending in the second direction Y andarranged in the first direction X, and a thin film transistor Tr whichis electrically connected to a gate line G and a source line S in eachpixel PX. Each pixel PX is defined by two adjacent gate lines G and twoadjacent source lines S. The thin film transistor Tr functions as aswitching element.

The first substrate SUB1 includes an edge SUB1 e in the non-display areaNDA, in which a plurality of pad electrodes PD and a plurality ofcontact holes CHa are formed. Each pad electrode PD is formed to overlapa corresponding contact hole CHa. Each of the source lines S and thegate lines G is drawn to the non-display area NDA and is electricallyconnected to a corresponding pad electrode PD. The wiring substrate 1 isformed to at least partially overlap the edge SUB1 e of the firstsubstrate SUB1 as depicted with the dotted line in the figure. Thewiring substrate 1 is, as described later, electrically connected to thepad electrode PD through the conductive material (which is not shown) inthe contact holes CHa.

FIG. 3 is a cross-sectional view of the display area DA of the displaydevice DSP of FIG. 1. Note that the example depicted in FIG. 3 shows areflective liquid crystal display device using a twisted nematic (TN)mode.

As shown in FIG. 3, the first substrate SUB1 includes, for example, asupport substrate 5, light shielding mask (light shield) LS, firstinsulating substrate 10, thin film transistor Tr, reflective layer 4,pixel electrode PE, and first alignment film AL1. The support substrate5 is, for example, a glass substrate. The light shielding mask LS isdisposed on the support substrate 5. The light shielding mask LS shieldsa laser beam. In the present embodiment, the light shielding mask LS isformed of a material which reflects a laser beam, and such a materialreflects excimer laser or the like. The first insulating substrate 10 isdisposed above the support substrate 5 and the light shielding mask LS.That is, the light shielding mask LS is disposed between the supportsubstrate 5 and the first insulating substrate 10. The first insulatingsubstrate 10 is formed of an organic insulating material such aspolyimide. The first insulating substrate 10 is covered with a firstinsulating film 11.

The thin film transistor Tr is disposed above the first insulating film11. In the example depicted, the thin film transistor Tr is structuredtop-gate type; however, it may be formed bottom-gate type. The thin filmtransistor Tr includes a semiconductor layer SC formed on the firstinsulating film 11. The semiconductor layer SC is covered with a secondinsulating film 12. The second insulating film 12 is disposed above thefirst insulating film 11.

A gate electrode WG of the thin film transistor Tr is formed on thesecond insulating film 12 to be directly above the semiconductor layerSC. The gate electrode WG is electrically connected to a gate line G (orformed integrally with the gate line G) and is covered with a thirdinsulating film 13. Furthermore, the third insulating film 13 isdisposed above the second insulating film 12.

The first insulating film 11, second insulating film 12, and thirdinsulating film 13 are formed of an inorganic material such as siliconoxide or silicon nitride.

A source electrode WS and a drain electrode WD are formed on the thinfilm transistor Tr. Furthermore, the source line S is formed on thethird insulating film 13. The source electrode WS is electricallyconnected to the source line S (or formed integrally with the sourceline S). The source electrode WS and the drain electrode WD areelectrically connected to the semiconductor layer SC through contactholes CH1 and CH2 passing through the second insulating film 12 and thethird insulating film 13. The thin film transistor Tr is covered with afourth insulating film 14. The fourth insulating film 14 is disposedabove the third insulating film 13. The fourth insulating film 14 isformed of an organic material such as transparent resin.

The reflective layer 4 is formed on the fourth insulating film 14. Thereflective layer 4 is formed of a highly reflective metal material suchas aluminum and silver. Note that the surface of the reflective layer 4(that is, the surface in the second substrate SUB2 side) has an asperityfor light dispersion.

The pixel electrode PE is formed on the fourth insulating film 14, andin the example depicted, it overlaps the reflective layer 4. Note thatthe reflective layer 4 can be formed at any position as long as it isopposed to the pixel electrode PE, and a different insulating film maybe interposed between the pixel electrode PE and the reflective layer 4.The pixel electrode PE contacts the drain electrode WD of the thin filmtransistor Tr through a contact hole CH3 which passes through the fourthinsulating film 14. The pixel electrode PE is formed of a transparentconductive material such as indium tin oxide (ITO) or indium zinc oxide(IZO). The pixel electrode PE is covered with the first alignment filmAL1.

On the other hand, the second substrate SUB2 is disposed above the firstsubstrate SUB1 and is opposed to the first substrate SUB1. The secondsubstrate SUB2 includes, for example, a second insulating substrate 30,light shielding layer BM, color filter CF, overcoat layer OC, commonelectrode CE, second alignment film AL2. The second insulating substrate30 is formed of a light transmissive material such as a glass substrateor a resin substrate.

The light shielding layer BM is formed on the second insulatingsubstrate 30 to be opposed to the first substrate SUB1. The lightshielding layer BM is formed to define each pixel PX to be opposed tothe gate line G, and the source line S of the first substrate SUB1, thelines of the thin film transistor Tr, and contact hole CH3. The lightshielding layer BM is formed of a light shielding metal material or ablack resin material.

The color filter CF is formed on the second insulating substrate 30 tobe opposed to the first substrate SUB1 and partly overlaps the lightshielding layer BM. Color filters CF are formed of resin materials ofdifferent colors such as red, blue, and green. A red color filtercorresponds to a red pixel, a green color filter corresponds to a greencolor pixel, and a blue color filter corresponds to a blue color pixel.Note that color filters CF may further include a white or a transparentcolor filter. Each boundary between color filters CF of different colorsis disposed to be opposed to a light shielding layer BM.

The overcoat layer OC covers the color filter CF. The overcoat layer OCis formed of a transparent resin material.

The common electrode CE is formed on the overcoat layer OC to be opposedto the first substrate SUB1. The common electrode is formed of atransparent conductive material such as ITO or IZO. The common electrodeCE is covered with the second alignment film AL2.

In the above-explained relationship of the first substrate SUB1 and thesecond substrate SUB2, the first alignment film AL1 and the secondalignment film AL2 are disposed to be opposed to each other. Therein, acertain cell gap is formed between the first substrate SUB1 and thesecond substrate SUB2 with spacers (which are not shown). The firstsubstrate SUB1 and the second substrate SUB2 are adhered together by asealant (which is not shown) with a cell gap formed therebetween. Theliquid crystal layer LQ is sealed within the first alignment film AL1and the second alignment film AL2. An optical element OD including apolarizer PL is disposed on the external surface 30B of the secondinsulating substrate 30. The optical element OD is disposed on thedisplay surface side.

FIG. 4A is a cross-sectional view of the display device DSP of FIG. 1including the non-display area NDA. Note that the second substrate SUB2here is structured substantially the same as the second substrate SUB2of FIG. 3, and the detailed description thereof will be omitted.Furthermore, a view of the first substrate SUB1 from the secondsubstrate SUB2 side is defined as a plan view.

As shown in FIG. 4A, the first substrate SUB1 and the second substrateSUB2 are adhered by a sealant SL. The liquid crystal layer LQ isdisposed between the first substrate SUB1 and the second substrate SUB2inside the area surrounded by the sealant SL. The sealant SL is formedin the non-display area NDA.

The support substrate 5 and the light shielding mask LS do not extend tothe edge of the first substrate SUB1 and are cut halfway. That is, thesupport substrate 5 and the light shielding mask LS do not extend to theside edge of the first substrate SUB1 in the edge SUB1 e side, which isshown in FIG. 2. Here, the first substrate SUB1 includes a first areaAR1 and a second area AR2. The first area AR1, in a plan view,corresponds to the area where the support substrate 5 and the lightshielding mask LS are disposed, and the second area AR2, in a plan view,corresponds to the area where the support substrate 5 and the lightshielding mask LS are not disposed. The support substrate 5 and thelight shielding mask LS overlap a part of the sealant SL in a plan view.The sealant SL is formed over the boundary of the first area AR1 and thesecond area AR2.

The pad electrode PD is formed above the first insulating substrate 10.In the example depicted, the first insulating film 11, second insulatingfilm 12, and third insulating film 13 are disposed between the padelectrode PD and the first insulating substrate 10. Furthermore, in theexample depicted, the pad electrode PD is a multilayer includingelectrodes P1 and P2. The electrode P1 is formed of, for example, indiumtin oxide as a transparent conductive material. The electrode P2 isdisposed above the electrode P1 and is formed of a conductive materialsuch as a metal material. The electrode P2 is formed in, for example, anisland shape. A contact hole CHa is formed passing through the firstinsulating substrate 10, first insulating film 11, second insulatingfilm 12, and third insulating film 13 to reach the pad electrode PD. Thepad electrode PD is formed in a position opposed to the contact holeCHa. The pad electrode PD and the contact hole CHa are, in a plan view,formed in the second area AR2 of the first substrate SUB1. Furthermore,the contact hole CHa is, in a plan view, formed at a positionoverlapping the sealant SL. Note that, in the present embodiment, thecontact hole CHa corresponds to a through hole passing through the firstinsulating substrate 10, first insulating film 11, second insulatingfilm 12, and third insulating film 13 to reach the pad electrode PD.

The signal line 6 is, in the example depicted, formed on the thirdinsulating film 13 and is formed in the same layer where the padelectrode PD is disposed. The signal line 6 is electrically connected tothe pad electrode PD. The signal line 6 and the pad electrode PD may beformed separately or integrally. In the example depicted, the signalline 6 is formed integrally with the electrode P2 of the pad electrodePD. The signal line 6 corresponds to the gate line G and source line Sof FIG. 2, a power source line, and various control lines.

Note that, in the example depicted, the signal line 6 and the padelectrode PD are disposed in the same layer where the source line S isdisposed; however, they may be disposed in a different layer.Furthermore, the signal line 6 and the pad electrode PD may be formed indifferent layers such that the signal line 6 and the pad electrode PDare electrically connected through a contact hole formed in aninterlayer insulating film therebetween. In the example depicted, thefourth insulating film 14 is disposed above the signal line 6 in thearea inside the sealant SL.

In the example depicted, the first substrate SUB1 further includes afirst spacer SP1 and a second spacer SP2. The first spacer SP1 isdisposed above the fourth insulating film 14 in the display area DA. Thefirst spacer SP1 is disposed on the first substrate SUB1 to be opposedto the second substrate SUB2 and projects toward the second substrateSUB2. The first spacer SP1 forms a certain cell gap between the firstsubstrate SUB1 and the second substrate SUB2. The first spacer SP1 isformed of a resin material based on, for example, acrylic resin.

The second spacer SP2 is formed on the pad electrode PD in thenon-display area NDA and is disposed between the pad electrode PD andthe second substrate SUB2. Furthermore, the second spacer SP2 isdisposed in a position overlapping the contact hole CHa. The secondspacer SP2 includes a first layer S1 and a second layer S2. In theexample depicted, the first layer S1 is disposed on the pad electrode PDand the second layer S2 is disposed on the first layer S1 to projecttoward the second substrate SUB2. Furthermore, the second layer S2contacts the second substrate SUB2. In the example depicted, the secondlayer S2 is tapered narrowing toward the second substrate SUB2. Thefirst layer S1 is, for example, formed of the same material used for thefourth insulating film 14 through the same manufacturing process, and isformed of a material which is different from that used for the sealantSL. The first layer S1 and the second layer S2 may be, for example, aresin layer formed of a resin material. In the present embodiment, thefirst spacer SP1 and the second layer S2 are formed of, for example, anegative photosensitive acrylic resin. Note that, in the exampledepicted, the sealant SL is disposed in both the outside and the insideof the first layer S1.

Note that, if the second spacer SP2 is realized as a single spacer, itmay be formed as a wall continuously extending in the first direction X.Or, if the second spacer SP2 is realized as a plurality of spacers, theymay be formed as discontinuous walls. Or, if the second spacer SP2 isrealized as a plurality of spacers, they may be formed as pillarsscattered arbitrarily. The second spacer SP2 may overlap with at least apart of the pad electrode PD in a plan view.

Furthermore, as depicted, if the second spacer SP2 includes a pluralityof layers, each of the layers can be formed of a material used for theinsulating film formed in the display area DA through the samemanufacturing process.

In the example depicted, the first spacer SP1 and the second spacer SP2are formed to be tapered toward the second substrate SUB2; however, theshape of the first spacer SP1 and the second spacer SP2 is not limitedto the example depicted, and they may be formed inversely to be taperedtoward the first substrate SUB1. Furthermore, in the example depicted,the second spacer SP2 is formed on the first substrate SUB1; however, itmay be formed on the second substrate SUB2.

The wiring substrate 1 includes a core substrate 200, a connection line100 disposed on the surface of the core substrate 200 to be opposed tothe liquid crystal display panel PNL, and driver 2 disposed on thesurface opposite to the surface of the core substrate 200 to be opposedto the liquid crystal display panel PNL.

The connection line 100 includes a projection T. The projection T of theconnection line 100 is formed in a position to overlap the contact holeCHa in a plan view. At least a part of the projection T is formed in thecontact hole CHa. The projection T is, for example, formed on theconnection line 100 through a plating method.

The driver 2 is electrically connected to the connection line 100through a through hole 110 formed in the core substrate 200. The driver2 functions as, for example, a signal supplier which supplies a signalto the liquid crystal display panel PNL for its drive. Note that theposition of the driver 2 is not limited to the above, and it may bedisposed on the surface of the core substrate 200 which is opposed tothe liquid crystal display panel PNL.

The liquid crystal display panel PNL and the wiring substrate 1 areelectrically connected and adhered together with an anisotropyconductive film 3 which is a conductive material. Specifically, theanisotropy conductive film 3 includes conductive particles CP dispersedin an adhesive agent. When the anisotropy conductive film 3 isinterposed between the wiring substrate 1 and the liquid crystal displaypanel PNL, they are pressed vertically in the third direction Z andheated to achieve electrical and physical connection therebetween. Theanisotropy conductive film 3 is, between the liquid crystal displaypanel PNL and the wiring substrate 1, filled inside the contact hole CHafrom the lower surface of the first insulating substrate 10 to contactthe first electrode P1 of the pad electrode PD. Furthermore, theanisotropy conductive film 3 contacts the projection T of the connectionline 100. Thereby, the connection line 100 is electrically connected tothe pad electrode PD and the signal line 6 through the anisotropyconductive film 3.

Specifically, the conductive particles CP in the anisotropy conductivefilm 3 are, in the contact hole CHa, interposed between the padelectrode PD and the projection T. With the projection T of theconnection line 100, when the wiring substrate 1 is pressed to theliquid crystal display panel PNL, the conductive particles CP arecrushed between the pad electrode PD and the projection T to establishelectrical connection therebetween. The conductive particles CP may beentirely formed of a metal material or may be formed of a resin materialwith metal coating of nickel or gold.

The projection T is opposed to the anisotropy conductive film 3 and thesecond spacer SP2 in the third direction Z. Here, strength of a materialcan be measured with a Young's modulus. The conductive particle CP ofthe anisotropy conductive film 3 has Young's modulus A, the projection Thas Young's modulus B, and the second spacer SP2 has Young's modulus C.Here, Young's modulus B of the projection T is greater than Young'smodulus A of the conductive particle CP and is less than Young's modulusC of the second spacer SP2.

In the present embodiment, the projection T, anisotropy conductive film3, and second spacer SP2 are opposed to each other in the thirddirection Z. The projection T is disposed in a position overlapping thecontact hole CHa. When the strengths of the second spacer SP2,projection T, and conductive particle CP are compared, the strength ofthe second spacer SP2 is greater than the others, the strength of theprojection T is less than the strength of the second spacer SP2, and thestrength of the conductive particle CP is less than the others.Therefore, when the wiring substrate 1 is pressed to the liquid crystaldisplay panel PNL, the conductive particle CP is crushed by the pressureforce from the projection T while the second spacer SP2 is relativelyunchanged by the pressure force from the projection T and the conductiveparticle CP. That is, the strength between the first substrate SUB1 andthe second substrate SUB2 with respect to the force applied in the thirddirection Z can be increased in the position where the wiring substrate1 is pressed to the liquid crystal display panel PNL, that is, theposition where the contact hole CHa is formed. Therefore, damage to theliquid crystal display panel PNL can be suppressed and the conductiveparticles CP can easily be deformed along the shape of the projection T.

Furthermore, since the second spacer SP2 is disposed in a positionoverlapping the contact hole CHa, the sealant SL is not disposed in aposition overlapping the contact hole CHa, and thus, there is no need ofselecting a material for the sealant SL in consideration of its Young'smodulus. Therefore, a material for the sealant SL can be selected frombroader choices and adhesion of the sealant SL can be improved.Furthermore, when the adhesion of the sealant SL is improved, anapplication area of the sealant SL can be reduced, and the non-displayarea NDA can be reduced accordingly. Furthermore, since the sealant SLis not necessarily applied to overlap the contact hole CHa, a loss ofproduction caused by misapplication of sealants SL can be suppressed.

Furthermore, in the present embodiment, the display device DSP includesthe wiring substrate 1 disposed below the liquid crystal display panelPNL (in the rear surface side which is opposite to the display surface)wherein the wiring substrate 1 and the liquid crystal display panel PNLare electrically connected through the conductive material (anisotropyconductive film 3 in the above example) in the contact hole CH in thesecond area AR2. Furthermore, the driver 2 is disposed below the liquidcrystal display panel PNL. Since the area of the first substrate SUB1 isnot required to be enlarged to mount the driver 2 or the wiringsubstrate 1 thereon, the first substrate SUB1 and the second substrateSUB2 can be formed substantially even. Furthermore, in the area wherethe first substrate SUB1 and the second substrate SUB2 are opposed toeach other, the active area ACT can be increased. That is, in thedisplay surface of the display device DSP of the present embodiment, thearea of the active area ACT used for display can be increased, and athinner bezel structure can be achieved.

Furthermore, since there is no need of a long flexible printed circuitused for the electrical connection between the part of the firstsubstrate SUB1 which is opposed to the second substrate SUB2 and thewiring substrate 1, or a space to accommodate a bent flexible printedcircuit, the display device DSP can be miniaturized. Furthermore, anelectronic device including the display device DSP can be miniaturized,too.

Furthermore, since a possible breakdown of the lines when the flexibleprinted circuit is bent can be avoided, the display device DSP can bemore reliable.

FIG. 4B is another cross-sectional view of the display device of FIG. 1including a non-display area. As compared to the liquid crystal displaypanel PNL of FIG. 4A, the structure of the second spacer SP2 isdifferent in the liquid crystal display panel PNL of FIG. 4B.

In the example of FIG. 4B, the second spacer SP2 includes the firstlayer S1 alone and does not include a second layer S2. Furthermore, thesealant SL is interposed between the first layer S1 and the secondsubstrate SUB2. As above, the second spacer SP2 may be a monolayer andmay not contact the second substrate SUB2.

FIG. 5 is a cross-sectional view of a variation of the display deviceDSP of the embodiment. As compared to the liquid crystal display panelPNL of FIG. 4A, the structure of the second spacer SP2 is different inthe liquid crystal display panel PNL of FIG. 5.

In the example of FIG. 5, the second spacer SP2 includes the first layerS1 alone and does not include a second layer S2. The first layer S1 isdisposed on the pad electrode PD and projects toward the secondsubstrate SUB2. The first layer S1 contacts the second substrate SUB2.In the example depicted, the first layer S1 is tapered toward the secondsubstrate SUB2. As above, the second spacer SP2 may be a monolayer. Atthat time, the first layer S1 is formed of the same material used forthe first spacer SP1 through the same manufacturing process.

FIG. 6 is a plan view of the first substrate SUB1 of the embodiment,showing the pad electrode PD, contact hole CHa, second spacer SP2, andsealant SL.

A plurality of pad electrodes PD and contact holes CHa are arranged inthe first direction X in the non-display area NDA in one end SUB1 e sideof the first substrate SUB1. That is, the pad electrode PD2 is adjacentto the pad electrode PD1. The second spacer SP2 extend in the firstdirection X in the non-display area NDA in the one end SUB1 e side ofthe first substrate SUB1. The second spacer SP2 overlaps the padelectrodes PD and the contact holes CHa in a plan view. That is, thefirst layer S1 overlaps the pad electrodes PD1 and PD2 in a plan view.In the example depicted, the sealant SL is disposed in both the insideand the outside the first layer S1.

FIG. 7 is a plan view of a variation of the first substrate SUB1 of theembodiment, showing a variation of the pad electrode PD, contact holeCHa, and second spacer SP2.

The pad electrodes PD, contact holes CHa, and signal lines 6 aredisposed in a zigzag arrangement. Such an arrangement of the padelectrodes PD allows a closer-packed arrangement of connection lines andthe like in the first direction X. In this variation, a greater numberof pad electrodes PD can be disposed as compared to the example of FIG.6. Since the pad electrodes PD can be disposed in a close-packedarrangement in one location of the one end SUB1 e, and the wiringsubstrate 1 can be miniaturized and made cost-effectively. The secondspacer SP2 extends in the first direction X in the non-display area NDAin the one end SUB1 side of the first substrate SUB1. In a plan view,the second spacer SP2 overlaps the pad electrodes PD and contact holesCHa disposed in a zigzag arrangement. That is, the first layer S1overlaps the pad electrodes PD1 and PD2 in a plan view.

Now, a manufacturing method of the display device DSP of the presentembodiment will be explained with reference to FIGS. 8 to 10. FIGS. 8 to10 are schematic cross-sectional views each showing a method of pressingthe wiring substrate 1 to the liquid crystal display panel PNL in thepresent embodiment. The structure above the pad electrode PD shown inFIGS. 8 to 10 is the same as that of the liquid crystal display panelPNL of FIG. 4A.

FIG. 8 is a cross-sectional view showing a first process in which thefirst substrate SUB1 and the second substrate SUB2 of the aboveembodiment are adhered together.

As shown in FIG. 8, the light shielding mask LS is initially formed onthe support substrate 5. The light shielding mask LS is formed in thefirst area AR1 of the first substrate SUB1. By applying an organicinsulating film on the support substrate 5 and the light shielding maskLS, a first insulating substrate 10 is formed. Then, the firstinsulating film 11, second insulating film 12, third insulating film 13,pad electrode PD, signal line 6, fourth insulating film 14, and firstalignment film AL1 are formed one after another. The fourth insulatingfilm 14 is formed on the signal line 6 in the first area AR1 while thefirst layer S1 is formed on the pad electrode PD in the second area AR2.The first space rSP1 is formed on the fourth insulating film 14 in thefirst area AR1 while the second layer S2 is formed n the first layer S1in the second area AR2. Then, the first alignment film AL1 is formed. Asabove, the first substrate SUB1 and the second substrate SUB2 areformed.

Then, the sealant SL is formed on the first substrate SUB1 or the secondsubstrate SUB2. In the present embodiment, a material of the sealant SLis applied from the above the second spacer SP2 of the first substrateSUB1. A liquid crystal material is dropped into the area surrounded bythe sealant SL, and the first substrate SUB1 and the second substrateSUB2 are adhered together.

Note that the sealant SL may be applied inside the second spacer SP2,that is, may be applied closer to the liquid crystal layer LQ side thanis the second spacer SP2. In that case, the second spacer SP2 functionsas a bank to suppress excessive spread of the sealant SL when the firstsubstrate SUB1 and the second substrate SUB2 are adhered together. Thus,the area of the sealant SL can be reduced and the non-display area NDAcan be reduced accordingly. At that time, the sealant SL is, forexample, disposed inside the second spacer SP2.

Then, laser LL is irradiated from the rear surface side of the supportsubstrate 5 to partly peel the support substrate 5 from the firstinsulating substrate 10. Here, in the present embodiment, the supportsubstrate 5 is formed of glass and the first insulating substrate 10 isformed of polyimide. The laser LL irradiated from the rear surface sideof the support substrate 5 reaches the surface 10A of the firstinsulating substrate 10 in the second area AR2. The first insulatingsubstrate 10 absorbs and resolves the laser LL at the interface betweenthe support substrate 5 and the first insulating substrate 10. Thereby,a space is created at the interface between the support substrate 5 andthe first insulating substrate 10. At that time, the laser LL does notreach the surface 10A of the first insulating substrate 10 by the lightshielding mask LS in the first area AR1, and thus, the interface betweenthe first insulating substrate 10 and the light shielding mask LS is notpeeled off.

FIG. 9 is a cross-sectional view showing a second process in which thesupport substrate 5 is partly peeled off from the first insulatingsubstrate 10 and the contact hole CHa is formed in the first substrateSUB1 after the first process of FIG. 8.

As shown in FIG. 9, after the laser irradiation, the support substrate 5is fixed to the first insulating substrate 10 through the lightshielding mask LS in the first area AR1 while the support substrate 5 isdetached from the first insulating substrate 10 in the second area AR2.Then, the support substrate 5 is cut at the boundary between the firstarea AR1 and the second area AR2 to remove the support substrate 5 fromthe second area AR2. Note that the position of cutting the supportsubstrate 5 is not limited to the position opposed to the end of thelight shielding mask LS. For example, the support substrate 5 may be cutat a position which is apart from the end of the light shielding mask LSand is not opposed to the light shielding mask LS.

After the support substrate 5 is detached from the first insulatingsubstrate in the second area AR2, the contact hole CHa is formed in thefirst substrate SUB1. Specifically, laser is irradiated from the lowerside of the first substrate SUB1 toward Lhe area overlapping the sealantSL, the contact hole CHa is formed through the first insulating film 11,second insulating film 12, third insulating film 13 to reach the contacthole CHa. In the present embodiment, laser with a wavelength of 258 nmor less should be used.

FIG. 10 is a cross-sectional view showing a third process in which thewiring substrate 1 is pressed to the liquid crystal display panel PNLafter the second process of FIG. 9.

As shown in FIG. 10, after the formation of the contact hole CHa in thefirst substrate SUB1, the wiring substrate 1 is pressed to the liquidcrystal display panel PNL using the anisotropy conductive film 3.Specifically, the anisotropy conductive film 3 is disposed between thewiring substrate 1 and the liquid crystal display panel PNL to beopposed to the contact hole CHa, and a force is applied from the lowerside of the wiring substrate 1 and the upper side of the liquid crystaldisplay panel PNL as shown by arrows in FIG. 10 and heat is appliedthereto. Thereby, the anisotropy conductive film 3 melts and permeatesinto the contact hole CH, and conductive particles included in theanisotropy conductive film 3 contact the pad electrode PD to achieveelectrical connection between the wiring substrate 1 and the liquidcrystal display panel PNL.

Through the above processes, the wiring substrate 1 is firmly adhered tothe liquid crystal display panel PNL.

FIG. 11 is a cross-sectional view of another variation of the displaydevice DSP of the above embodiment. In the example of FIG. 11, thedisplay device is an organic electroluminescent display device.

Initially, the structure of the display device in a display element part120 will be explained. Note that elements structured the same as thoseof the above example will be referred to by the same reference numbersand detailed description thereof will be omitted.

As in FIG. 11, the first substrate SUB1 includes, for example, a supportsubstrate 5, light shielding mask LS, first insulating substrate 10,switching elements SW1, SW2, and SW3, and organic electroluminescent(EL) elements OLED1, OLED2, and OLED3. The light shielding mask LS isdisposed between the support substrate 5 and the first insulatingsubstrate 10. Switching elements SW1 to SW3 are formed on the firstinsulating film 11. The reflective layer 4 is formed on the fourthinsulating film 14.

Organic EL elements (light emitting elements) OLED1 to OLED3 aredisposed between the first substrate SUB1 and the second substrate SUB2.Furthermore, the organic EL elements OLED1 to OLED3 are formed on thefourth insulating film 14. In the example depicted, the organic ELelement OLED1 is electrically connected to the switching element SW1,the organic EL element OLED2 is electrically connected to the switchingelement SW2, and the organic EL element OLED3 is electrically connectedto the switching element SW3. Each of the organic EL elements OLED1 toOLED3 is structured as a top-emission type which emits whit light towardthe second substrate SUB2. The organic EL elements OLED1 to OLED3 havethe same structure.

The organic EL elements OLED1 includes a positive electrode PE1 formedon the reflective layer 4. The positive electrode PE1 contacts the drainelectrode WD of the switching element SW1 and is electrically connectedto the switching element SW1. Similarly, the organic EL element OLED2includes a positive electrode PE2 which is electrically connected to theswitching element SW2 and the organic EL element OLED3 includes apositive electrode PE3 which is electrically connected to the switchingelement SW3.

The organic EL elements OLED1 to OLED3 each include an organic lightemitting layer ORG and a common electrode (negative electrode) CE. Theorganic light emitting layer ORG is disposed to correspond to each ofthe positive electrodes PE1 to PE3. The common electrode CE ispositioned above the organic light emitting layer ORG. In the exampledepicted, the organic EL elements OLED1 to OLED3 are defined by ribs 15.Note that, although this is not depicted, each of the organic ELelements OLED1 to OLED3 is, preferably, sealed by a transparentshielding film.

The display element part 120 is an area of the first substrate SUB1 inwhich a plurality of switching elements and organic EL elements OLED arearranged, and thus, the display element part 120 is a substantialdisplay area for the image display.

The second substrate SUB2 includes a color filter layer 220 and the likeon the inner surface 30A side of the second insulating substrate 30. Thecolor filter layer 220 includes color filters CF1, CF2, and CF3. Thecolor filter CF1 is opposed to the organic EL element OLED1 and is ablue color filter which passes light of blue wave length in white light.The color filter CF2 is opposed to the organic EL element OLED2 and is agreen color filter which passes light of green wave length in whitelight. The color filter CF3 is opposed to the organic EL element OLED3and is a red color filter which passes light of red wave length in whitelight.

The display element part 120 of the first substrate SUB1 and the secondsubstrate SUB2 are adhered by a transparent adhesive layer 41.

Tn the above display device, when the organic EL elements OLED1 to OLED3emit light, the light (white light) irradiated from the elements OLED1to OLED3 exits through the color filters CF1, CF2, and CF3. Therein, thelight of blue wave length in the white light irradiated from the organicEL element OLED1 passes the color filter CF1. Additionally, the light ofgreen wave length in the white light irradiated from the organic ELelement OLED2 passes the color filter CF2, and the light of red wavelength in the white light irradiated from the organic EL element OLED3passes the color filter CF3. Therefore, color image display can beachieved.

Now, the structure of the display device in a bezel area PRP will beexplained.

The first substrate SUB1 includes, for example, the support substrate 5,light shielding mask LS, first insulating substrate 10, pad electrodePD, signal line 6, and third spacer SP3. A contact hole CHb is formed topass through the first insulating substrate 10, first insulating film11, second insulating film 12, and third insulating film 13 to reach thepad electrode PD. The contact hole CHb corresponds to a through hole.The signal line 6 is disposed on the third insulating film 13 in thesame layer in which the pad electrode PD is disposed.

The third spacer SP3 is disposed on the pad electrode PD. The thirdspacer SP3 includes the first layer S1, second layer S2, and third resinlayer S3. In the example depicted, the first layer S1 is disposed on thepad electrode PD, the second layer S2 is disposed on the first layer S1,and the third resin layer S3 is disposed on the second layer S2. Thefirst layer S1 is formed of the same material used for the fourthinsulating film 14 through the same manufacturing process. The secondlayer S2 is formed of the same material used for, for example, the firstspacer SP1 through the same manufacturing process. The third insulatinglayer S3 is formed of the same material used for, for example, thespacer formed in the display element part 120 through the samemanufacturing process. Note that the adhesive layer 41 is disposed inboth the inside and the outside the first layer S1 as with the sealantSL of FIG. 6.

The wiring substrate 1 is disposed in the rear surface side of the firstsubstrate SUB1. The pad electrode PD and the connection line 100 of thewiring substrate 1 are electrically connected to each other through theanisotropy conductive film 3. The same advantages obtained in the aboveembodiment can be achieved in such an organic EL display device of abovevariation.

As can be understood from the above, the present embodiment can achievea compact and thin-bezel display device.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A display device comprising: a first substrateincluding an insulating substrate with a through hole, a first padelectrode disposed above the insulating substrate, and a signal lineelectrically connected to the first pad electrode; a second substratedisposed to be opposed to the first substrate; a first layer disposedbetween the first pad electrode and the second substrate; a wiringsubstrate including a connection line and disposed below the insulatingsubstrate; and a conductive material disposed within the through hole toelectrically connect the first pad electrode and the connection line,wherein the through hole is formed in a position overlapping the firstlayer.
 2. The display device of claim 1, further comprising a spacerincluding the first layer and a second layer disposed on the firstlayer.
 3. The display device of claim 1, wherein the first layer isformed in the first substrate.
 4. The display device of claim 2, whereinthe second layer contacts the second substrate.
 5. The display device ofclaim 4, wherein the second layer is tapered.
 6. The display device ofclaim 1, wherein the first layer contacts the second substrate.
 7. Thedisplay device of claim 6, wherein the first layer is tapered.
 8. Thedisplay device of claim 1, wherein the first substrate further includesa first area, a second area adjacent to the first area, and a supportsubstrate disposed in the first area.
 9. The display device of claim 1,wherein the connection line has a first Young's modulus, the first layerhas a second Young's modulus, the conductive material has a thirdYoung's modulus, where the first Young's modulus is greater than thethird Young's modulus and is less than the second Young's modulus. 10.The display device of claim 1, wherein the first pad electrode include afirst electrode contacting the conductive material, and the firstelectrode is formed of a transparent conductive layer.
 11. The displaydevice of claim 10, wherein the first pad electrode includes a secondelectrode disposed on the first electrode, and the second electrode isformed of a metal material.
 12. The display device of claim 1, furthercomprising a light emitting element disposed between the first substrateand the second substrate, and an adhesive layer which adheres the firstsubstrate and the second substrate, wherein the adhesive layer ispositioned inside the first layer in a plan view.
 13. The display deviceof claim 12, wherein the adhesive layer is positioned outside the firstlayer in a plan view.
 14. The display device of claim 1, furthercomprising a liquid crystal layer held between the first substrate andthe second substrate, and a sealant which adheres the first substrateand the second substrate, wherein the sealant is positioned inside thefirst layer in a plan view.
 15. The display device of claim 14, whereinthe sealant is positioned outside the first layer in a plan view. 16.The display device of claim 1, wherein a sealant is interposed betweenthe first layer and the second substrate.
 17. The display device ofclaim 1, wherein the first substrate includes an insulating film formedof a material used for the first layer.
 18. The display device of claim1, further comprising a second pad electrode adjacent to the first padelectrode, wherein the first pad electrode and the second pad electrodeoverlap the first layer in a plan view.